I, for one, find a Tauren rogue plausible. A combat rogue. There are a fair number of Tauren pirates in the game, most prominently Fleet Master Seahorn and Mr. Smite. Pirates and combat rogues have a lot in common, not the least of which being that the second word in combat's description, after "a", is "swashbuckler."

Goblin druids, now those are improbable. Draenei warlocks would be truly bizarre.

Hopefully none. The game could use more personality, instead of hundreds of thousands of Blood Elf Paladins.

"I realized it is the struggle itself that is the most important. We must strive to be more than we are. It does not matter that we will never reach our ultimate goal. The effort yields its own rewards." -Data

Actually the Highborne mages arent quite to the night elves what the Eredar Warlocks are to the draenai. The eredar being much much much worse to the draenai. and hell given the NE's experiences in the past with the legion, the eredar are worse in their eyes too.

the current highborne mages are redeeming themselves in the NE's eyes bit by bit, except for troubles here and there (side glance at Maiev).

ofcourse theres theres not much differentiation going on in the eyes of the night elves for the high elves and especially the blood elves, who they make no distinction from their highborne roots, especially since a lot of their behaviour (less for high elves) is about what the highborne of the past were like.

Sorry, but like goblins and worgen before them and draenai before that - any race can be a death knight for quote "coolness reasons".

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No Tauren was trained either.

Tauren Paladins are more like Druids than they are Paladins. They're simply Paladins for gameplay reasons. Most Druids use the Moon to channel their power. Sunwalkers are basically Druids that use the Sun as their source.

As for Worgen Paladins - Paladins lose their abilities if they willingly commit a sin (according to the paladin code). My thinking is that Worgens can't be paladins based on that fact, as everything they did was quite willingly sinful and brutal and such. Priests can channel the Light based on the strength of their faith alone -A Worgen Paladin may have lost their connection to the Light because they can remember everything they've done as a Worgen, and due to that, may no longer be a Paladin and is either a Warrior or Priest now (Paladins are basically, Priests in Plate - that's how they started out at least). While semi-sketchy, it seems like the most likely lore explanation for them being unable to be Paladins while being Priests.

As for Death Knights, Goblins have been in the service of both the Alliance and Horde as mercenaries since forever, It makes since for them to be Death Knights, due to that fact alone. Lorewise, most Worgen Death Knights are those created from Arugal - who was resurrected and had joined the Lich King's forces prior to Wrath. While the curse makes them immune to the Val'kyr, the Lich King is a far superior being and should've had no trouble raising Worgen for his Death Knights himself (another explanation could be that the Lich King being alive and active could've made them more powerful than they were on their own under Sylvanas). The player character is described as "his personal champion" after all so, while Stu/Sue-ish, it's likely the Lich King raised the Worgen Death Knights himself. As for Draenei, there's nothing that states they cannot be raised into Undeath - they just lose everything that connects them to the Naaru, and they become what they've been fighting against their whole lives. After all, even A'dal was unable to cleanse the Plague from that one Crusader in that quest chain (as were other notable characters), so if he can't cure it, it can be assumed he cannot prevent it either.

As for other cases:
Draenei Warlocks: The Draenei are a race devoted wholly to fighting the Legion. It's been indoctrinated into them since Day 1, and every single day of their lives has been spent fighting or preparing for the final war against the Legion. For a race that is wholly connected to the Light and the Naaru (think about their racial spell), becoming a Warlock would not only be heretical, it would be seen as a betrayal of their entire race. Any individual who did so would be an outcast, having turned against the core concepts of their race and everything their family and friends have fought against. If not exiled, they'd be killed outright. Draenei strongly dislike Warlocks in the Alliance as it is; a Draenei Warlock would be seen as a walking time bomb, if not a perversion of their cultural identity (this all assumes a Draenei gets to the point that they're willing to turn their back on everything).

Night Elf Warlocks: Much like Draenei, the Night Elves are, as a race, devoted to Nature. Warlocks are a perversion of that nature, and are unlikely to be seen in Night Elf society. After seeing what the Legion did 10,000 years ago, it's still very unlikely for them to become Warlock anytime soon. As with the Draenei, any Night Elf Warlock would be seen as a heretic and an outcast. While all it takes is a few steps from mage to fel power, Night Elf Magi are still few and far in between, and are still wholly distrusted and closely watched in Night Elf culture. There is a stronger chance to see them before Draenei Warlocks, but not by much.

I don't think Undead Paladins or Druids and Shaman for that matter, will ever be seen anytime soon. Undead Holy/Disc Priests are seen as heretics and martyrs as it is, since even channelling the Light a little bit, or even getting healed by it, hurts like hell (which is why most, if not all, are Shadow; hell, there's even a Church for the Undead based solely on that, a complete opposite of Stormwind's church). An Undead Paladin would likely die from the pain of being a Vessel/Champion of the Light (if such a thing were even possible). Undead are, by default, a perversion against Nature (something that is dead should not be alive). Druids and Shaman, both strongly connected to it, are unlikely for this reason. While these 3 race/class combos would be undoubtedly badass (hell, I want one, even if the lore-me doesn't), it's unlikely given these reasons.

Nothing else really stands out to me as impossible. If I think of something, I'll come back and edit this, or just add a new post.

I think if you're going to say anyone can learn to be a Rogue or Warrior or Hunter then yeah, that's true. But in theory there's no real reason why a Human couldn't become attuned enough with nature to be a druid, or a Troll couldn't learn about the Light and become a Paladin. Certainly it's possible for Night Elves to be Warlocks. The point is, such people aren't representative of the race as a whole and that's what the class-race dynamic is supposed to reflect. Taurens COULD learn to be Rogues, but as a whole the playable Tauren tribe would not. A gnome could become a Paladin but that's certainly a rare thing. Therefore they aren't playable options.

Originally Posted by Leotheras the Blind

Yes, and that's why DC (mostly) sucks and Superman is the worst super hero of all time.

To be fair, Golden Age was even worse! They just made new shit up every week.

And Marvel had a Silver Age too. And really, modern comics are far from immune to doing crazy fucked up things.

Let's just say that comics are a very old continuous medium. TV shows jump the shark after what, 5 years max? Comics have been running since the 30s! They've piled 16 shark jumps on top of each other!

Originally Posted by Grubjuice

I can agree with that statement

but Dark Phoenix was actually a psychic clone while the real Gene Grey was trapped underwater in jamaica bay?
c'mon.

Draenei warlock. Draenei get deformed from exposure to del magic. A draenei warlock would likely get his/her face beaten in by a vindicator pretty much instantly.

Undead druid. Undeath is completely unnatural and an affront to the balance of nature. An undead that wished to restore balance to nature would probably feel compelled to kill himself. I doubt they could even access the power of nature anyway.

Night elf warlock. They'd be killed on sight by other night elves.

Pandaren death knights. There weren't any pandaren around during BC/Wrath transition for them to be death knights.

Goblin and orc druids. They view nature as something to exploit for personal gain, not something to protect.

Because whether they learned it our not they do not need it, They are immune to undead. Humans use it because they are not.

This argument really doesn't make any sense.

Ultraxion yells: I am the beginning of buttonclickers...the button which blots out my wipe mechanic...the click which tolls my doom...
Ultraxion yells: For this moment ALONE was I made. Look upon your button, mortals, and click!

But srsly i found it stupid since start. Gnomes don't have the Dwarves power to be warriors. What chance little gnome have againt Tauren with chunk of tree in his hands or Orc fueled by a Deamon Blood ?